2004 Chev Tahoe Case Study No Communication

2004 Chevrolet Tahoe -No Generic Communication

2004 Chevrolet Tahoe This vehicle was located at

Sullivan Pontiac Buick. The concern was that the vehicle would communicate with the TECH 2 scantool, but would not communicate with APPLUS equipment.

2004 Chevrolet Tahoe

2004 Chevrolet Tahoe

2004 Chevrolet Tahoe

2004 Chevrolet Tahoe The first step is to review

communication schematics for the vehicle you are working on. This is a Class 2 communication protocol.

SP205 Schematic Part I

SP205 Schematic Part II

Splice Pack 205

Spice Pack 205-Connector Endview

2004 Chevrolet Tahoe The second step is to scope the

Class 2 line. A BOB was attached to the vehicle at the DLC. The scope probes were placed in Pin # 2 on the BOB. Class 2 level was below threshold.

Class 2 Level below Threshold

The class 2 level was too low.

2004 Chevrolet Tahoe The third step was to take the comb

out of the splice pack and jumper each module line. Every terminal on the SP205 was at threshold except pin# H

Class 2 Level at Threshold

This was the voltage level at all pins except pin# H.

SP205 Schematic Part II

Class 2 Level below Threshold

This was the voltage level denoted at pin# H.

Summary Terminal H was backed out of the

SP205 connector and communication was restored on this vehicle at a generic level. A loading effect is taking place on this circuit per a wiring or module related issue.